[Freeipa-devel] [PATCH] 0197 client referral support for trusted domain principal

[Sumit Bose]

On Thu, Oct 08, 2015 at 01:12:56PM +0200, Martin Basti wrote:
> 
> 
> On 10/08/2015 12:36 PM, Alexander Bokovoy wrote:
> >On Mon, 05 Oct 2015, Sumit Bose wrote:
> >>On Thu, Sep 03, 2015 at 06:22:05PM +0300, Alexander Bokovoy wrote:
> >>>On Thu, 03 Sep 2015, Alexander Bokovoy wrote:
> >>>>Hi,
> >>>>
> >>>>attached patch adds support for issuing client referrals when FreeIPA
> >>>>KDC is asked to give a TGT for a principal from a trusted forest.
> >>>>
> >>>>We return a matching forest name as a realm and KDC then returns an
> >>>>error pointing a client to a direction of that realm. You can see how
> >>>it
> >>>>looks with http://fpaste.org/263064/14412849/ -- it shows behavior for
> >>>>both 'kinit -E -C' and 'kinit -E'.
> >>>>
> >>>>Note that current MIT Kerberos KDC has a bug that prevents us from
> >>>>responding with a correct client referral. A patched version for
> >>>Fedora
> >>>>22 is available in COPR abbra/krb5-test, a fix to upstream krb5 is
> >>>>https://github.com/krb5/krb5/pull/323/ and I'm working on filing bugs
> >>>to
> >>>>Fedora and RHEL versions.
> >>>>
> >>>>With the version in my abbra/krb5-test COPR you can test the patch
> >>>with
> >>>>the help of kinit like fpaste URL above shows.
> >>>After discussing with Simo and Sumit, here is updated patch that
> >>>operates directly on 'search_for' krb5_principal and avoids
> >>>strchr()/strrchr() and additional memory allocations -- it uses
> >>>memrchr() to find '@' in the last component of the search_for principal
> >>>and considers the part of the component after '@' as an enterprise
> >>>realm
> >>>to check.
> >>
> >>The patch looks good and works as advertised. I've tested in a IPA
> >>domain which trusts two different forests. All requests to the forest
> >>roots and child domains where properly redirected. I tested with your
> >>krb5 test build and with MIT Kerberos 1.14 which contains the needed
> >>fix.
> >>
> >>Nevertheless there are a view points I want to discuss:
> >>
> >>- missing support for AD's Alternative Domain Suffixes, this is
> >> important to allow AD users to login in with their "Email-Address"
> >> (which is the typical reference for a user name with an alternative
> >> domain suffix). I think this is not strictly related to the given
> >> ticket, so it can be solved in the context of a new ticket, do you
> >> agree?
> >Yes, please add a separate ticket. We need to do a bit more here:
> >- extend schema to allow adding the attribute for alternative domain
> >  suffixes
> >- switch to use different DCE RPC call to retrieve forest trust
> >  information. We can do it now that we have a call-out mechanism and
> >  can isolate access to TDO credentials (this is long standing issue
> >  first identified by Metze as part of cross-forest trust support for
> >  Samba 4.3)
> >- Make possible to associate alternative domain suffixes with IPA
> >  realm. We have support for realm domains already but we don't allow
> >  to use them yet for the same call as in the above item.
> >
> >>- referrals from outside. If I call 'kinit -E admin at IPA.DOMAIN' from a
> >> client in a trusted AD forest I get a 'Client not found in database'
> >> error because AD tends to use lower case domain names in the referal
> >> response. The request is still properly send to the IPA KDC because
> >> DNS does not care about the case. The IPA KDC processes the request
> >> with the principal 'user\@IPA.DOMAIN at ipa.domain' until
> >> ipadb_is_princ_from_trusted_realm() returns KRB5_KDB_NOENTRY becasue
> >> it detects that the principal is from the local realm. I think it
> >> would be good to enhance your patch to handle this case.
> >This is a separate bug too. Please file a ticket.
> >
> >
> >>- S4U2Self. MIT Kerberos 1.14 can now properly handle S4U2Self across
> >> domain and forest boundaries (I tested this in a setup with 2 AD
> >> forests with request going from a child domain to a child domain in
> >> the other forest. Unfortunately it is currently not working with IPA
> >> in neither direction (I guess the case issue from above might be the
> >> reason for the incoming request to fail). Here I think a new ticket
> >> would to good as well because some research might be needed and the
> >> issue might even be in the MIT code. (If you want to run some tests I
> >> can give you access to my test environment.)
> >I think we want to have this working, thus a ticket is due here. This is
> >something we'll most likely require for some advanced 2FA operations for
> >AD users.
> >
> >>Let me know if you prefer to handle the issues with other tickets, then
> >>I would ACK the patch as it is.
> >Please file separate tickets.
> >
> 
> Summit, Alexander, is this patch ACKed or not?

yes, ACK, I'll file the tickets mentioned above.

bye,
Sumit

> 
> Martin